Effect of drying on damping and stiffness of nailed joints between wood and plywood PublicDeposited

Descriptions

Wood components, usually assembled in green or semi-dry condition,
dry during the initial service life. To evaluate the effect
of such drying on joint stiffness and damping, cyclic-load tests
were conducted on single-nail joints of wood and plywood that had
been exposed to drying cycles. Additional effects studied were the
surface condition of lumber and level of cyclic load. Tests showed
that the stiffness decreased with load but remained the same for
the planed and unplaned surface condition. The surface condition
did affect the damping ratio when a tight interlayer contact existed.
The effect of load level on damping ratio depended on the drying-produced
gap between the lumber and plywood. The results show that
the damping ratio and slip modulus were significantly smaller for
joints with the gap than for those without it.
In a preliminary study the possibility was examined of using a
free-vibration test for measuring the damping ratio of nailed
joints. No simple arrangement could be devised for a reliable prediction
of the ratio.